Patent GB-878366-A (GB)
Title: Automatic variable speed transmission system for motor vehicles
Inventor: ELLIS FREDERICK EDWARD
IPC: B60K17/06
Filed: 1958-05-01
Abstract: 878,366. Change-speed gear. AUTOMOTIVE PRODUCTS CO. Ltd., and REID, H. C. May 1, 1959 [May 1, 1958], No. 13949/58. Class 80 (2). [Also in Group XXXIV] A change-speed gear and control for a motor vehicle comprises in series an hydrodynamic torque converter 108 or speed-responsive clutch, a two-speed and reverse bevel epicyclic gear 22 having automatic gear-changing means which hold stepped planet pinions 21, 22 against rotation when the planet carrier rotates about the gear axis, a coaxial forward and reverse clutch 47, and a liquid pressure control system having an engine-driven front pump FP, an output driven rear pump RP, and a reverse gear control RS which on movement of a forward-reverse lever 59 applies a brake BT (76, Fig. 1) which holds the forward and reverse clutch members 54, 55. Function summary.-Three embodiments are described. In the first, Figs. 1 and 13, an output speed-responsive governor valve CV enforces reduced ratio in the planet gear by applying a reaction brake 37 to the planet carrier at all speeds from 0 to 25 m.p.h. Above that speed the governor releases the brake 37 but reduced drive reaction is maintained by a parallel oneway detent 38, until the driver initiates upshift by momentarily closing the engine throttle, the ensuing rotation of the planet carrier under torque reversal causing planetary masses 43 to brake the planet pinions, and producing solid drive when the throttle is reopened. Return downshift is fully automatic under load. At a higher speed, 40 m.p.h., the governor valve CV engages a lock-up clutch 124 by-passing the torque converter. Accelerator kick-down applies the planet carrier brake 37 for downshift in the gear, whilst leaving the converter lock-up clutch engaged. The second embodiment, Fig. 14, substitutes a direct-drive friction clutch 71 for the planet mass control. The governor valve CV, Fig. 15 (not shown) first releases the reaction brake 37, leaving the planet carrier reacting on its oneway detent 38 and at 40 m.p.h. engages the direct-drive clutch 71 for upshift. Accelerator kickdown is by opposing the governor. The third embodiment, Figs. 16 and 17 (not shown) combines the two preceding systems. Shift of the forward-reverse clutch dog 47 is facilitated by the input brake 76, above referred to. A park-lock pawl wheel 104 is provided. Gear arrangement.-The gear comprises in series between input and output shafts 102, 16 an hydrodynamic torque converter 108 with lock-up clutch 124; a bevel planet train the planets 21, 22 of which mesh respectively a side wheel 11 driven from the lock-up clutch or converter turbine 112 through a shaft 10, and forward and reverse side wheels 27, 45 connected through an intermediate shaft 17 and sleeve 46 to the forward and reverse clutch members 54, 55 which are selectively clutched to output by a dog clutch 47. The planet carrier 24 is held against reverse rotation about the shaft 17 by a one-way detent 38 and can be held by a controllable brake 37 for two-way reduced drive and for reverse. The planet pinions are prevented from rotating about their shaft for direct drive by masses 43 attached to the planet pinions 21 Fig. 1, as described in Specification 851,172 or by a direct-drive clutch CL, Fig. 14, which locks together the shaft 10 and intermediate shaft 17. In Fig. 17 (not shown) a combination of masses on the planet pinions and a direct-drive clutch is used. Torque converter.-The torque converter 108 has an input-driven impeller 113 which through a sleeve 109 drives the front pump FP, a turbine 112 splined to the shaft 10 and a reactor 114 held against reverse rotation by a detent 115. Liquid feed and exhaust lines 136, 138 and a fan 126 on the converter impeller 113 are provided. Lock-up clutch.-124, Fig. 1, comprises an output disc 123 which is clamped to a back plate 107 by liquid pressure applied through a line 169 to a freely rotatable presser plate 119. Direct-drive clutch.-CL, Fig. 14, comprises friction discs 71 alternately splined to a driven drum 51, 31, 29 connected to the shaft 10 and bevel wheel 11 and a driven member 70 splined to the intermediate shaft 17. The clutch is engaged by liquid pressure supplied to a piston 72 which acts through a Belleville spring 74 on a presser plate 7 5 clamping the discs 71 against the back plate 29. Brakes.-The band brake 76 which holds the input bevel 11 during operation of the forwardreverse lever 59 is operated by pressure liquid supplied to a single piston whilst the planet carrier brake 37 is actuated by two pistons 148, 149 working in tandem in separate cylinders 150, 151 energized simultaneously. Fluid system.-Forward and reverse gear type pumps FP, RP, Fig. 13, supply pressure liquid to the input line 168 of the governor valve CV, the forward-reverse valve RS and through a restrictor RO to the torque converter CT, the outflow from the converter being led through a non-return valve NRV2 and sprayed over the gearing to lubricate the latter. The forwardreverse valve RS, 79, Fig. 5, is opened by slight downward movement of the shift lever 59, which movement is transmitted through an upwardly spring-pressed member 63 and spring 68 to move down the valve 79 against a return spring 84 thus supplying pressure liquid to the brake BT (76, Fig. 1). The governor valve CV as shown in Fig. 13 supplies pressure liquid to the planet carrier brake BPC below a predetermined speed (25 m.p.h.) and to the torque converter lock-up clutch LC above another predetermined speed (40 m.p.h.). An override accelerator kickdown valve 166, which normally has no effect on the system, when operated supplies pressure liquid through a passage 173 to both the planet carrier brake BPC and lock-up clutch LC. In Fig. 15 (not shown) the rear pump exhausts the front pump at a predetermined pressure and non-return valves are provided in the delivery lines for both pumps. The separate override valve 166 is omitted, the override acting directly on the governor valve itself. Operation.-With the engine running and the forward-reverse lever set to neutral as shown, the front pump FP supplies pressure fluid to the torque converter CT and through the governor valve CV which is positioned as shown since the vehicle is stationary, to engage the planet carrier brake BPC. For first ratio the shift lever 59 is first depressed to open the valve RS whereupon the brake BT is engaged stopping the input bevel 11 and thereby stopping the clutch members 54, 55. The dog clutch 47 is then engaged with the forward clutch member 55 the clutch sleeve 47 being held in position by a ball detent 90a. Release of the shift lever closes the valve RS and releases the brake BT, whereupon the vehicle is accelerated through the torque converter and reduction gear. The planet carrier brake BPC remains engaged in first ratio until the vehicle speed reaches 25 m.p.h., when the governor valve CV releases the brake BPC, the planet carrier then being held against reverse rotation by the detent 38. In Fig. 1, upshift is effected on momentary throttle closure, the carrier 24 rotating forwardly whilst the resistance of the masses 43 to rotation about their own axes produces solid drive (as described in Specification 851,172). Above the second predetermined speed the governor valve CV energizes the lock-up clutch LC of the torque converter. The Fig. 14 embodiment operates similarly, but with the modification described above with reference to Fig. 15 (not shown). Accelerator kickdown for both forms is also as above described. Specifications 878,364 and 878,365 also are referred to.